A Case Study to Identify the Drug Conjugation Site of a Site-Specific Antibody-Drug-Conjugate Using Middle-Down Mass Spectrometry

Oscar Hernandez-Alba (1) , Stéphane Houel (2) , Steve Hessmann (1) , Stéphane Erb (1) , David Rabuka (3) , Romain Huguet (2) , Jonathan Josephs (2) , Alain Beck (4) , Penelope Drake (3) , Sarah Cianférani (1)

1 DSA-IPHC - Département Sciences Analytiques et Interactions Ioniques et Biomoléculaires
2 ThermoFisher Scientific
3 Catalent Biologics West
4 Centre d'Immunologie Pierre Fabre

Middle-down mass spectrometry (MD MS) has emerged as a promising alternative to classical bottom-up approaches for protein characterization. Middle-level experiments after enzymatic digestion are routinely used for subunit analysis of monoclonal antibody (mAb)-related compounds, providing information on drug load distribution and average drug-to-antibody ratio (DAR). However, peptide mapping is still the gold standard for primary amino acid sequence assessment, post-translational modifications (PTM), and drug conjugation identification and localization. However, peptide mapping strategies can be challenging when dealing with more complex and heterogeneous mAb formats, like antibody-drug conjugates (ADCs). We report here, for the first time, MD MS analysis of a third-generation site-specific DAR4 ADC using different fragmentation techniques, including higher-energy collisional- (HCD), electron-transfer (ETD) dissociation and 213 nm ultraviolet photodissociation (UVPD). UVPD used as a standalone technique for ADC subunit analysis afforded, within the same liquid chromatography-MS/MS run, enhanced performance in terms of primary sequence coverage compared to HCD- or ETD-based MD approaches, and generated substantially more MS/MS fragments containing either drug conjugation or glycosylation site information, leading to confident drug/glycosylation site identification. In addition, our results highlight the complementarity of ETD and UVPD for both primary sequence validation and drug conjugation/glycosylation site assessment. Altogether, our results highlight the potential of UVPD for ADC MD MS analysis for drug conjugation/glycosylation site assessment, and indicate that MD MS strategies can improve structural characterization of empowered next-generation mAb-based formats, especially for PTMs and drug conjugation sites validation.

Domaines: Chimie

Oscar Hernandez-Alba, Stéphane Houel, Steve Hessmann, Stéphane Erb, David Rabuka, et al.. A Case Study to Identify the Drug Conjugation Site of a Site-Specific Antibody-Drug-Conjugate Using Middle-Down Mass Spectrometry. Journal of The American Society for Mass Spectrometry, 2019, 30 (11), ⟨10.1007/s13361-019-02296-2⟩. ⟨hal-02341587⟩